FFB3946 Equivalent & Substitute Parts

Part Overview

The FFB3946 is an obsolete bipolar junction transistor (BJT) array manufactured by onsemi, featuring complementary NPN and PNP transistors in a surface mount SC-88 (SC-70-6) package. This part integrates dual transistor functionality with a maximum collector current of 200mA, collector-emitter breakdown voltage of 40V, and a transition frequency of 200MHz. The product status of obsolete necessitates identification of active equivalent and substitute parts to maintain design continuity and ensure long-term component availability for new production and field replacements.

Key Parameters

Parameter	FFB3946 Value	Unit
Transistor Type	NPN, PNP	—
Current - Collector (Ic) Max	200	mA
Voltage - Collector Emitter Breakdown (Max)	40	V
Vce Saturation (Max)	250 @ 1mA, 10mA	mV
DC Current Gain (hFE) Min	100 @ 10mA, 1V	—
Power - Max	300	mW
Frequency - Transition	200	MHz
Operating Temperature Range	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	6-TSSOP, SC-88, SOT-363	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the FFB3946 is determined by strict alignment of electrical and mechanical parameters. The critical parameters governing substitution are:

Electrical Parameters:

Transistor configuration (NPN/PNP complementary pair)
Maximum collector current (200mA minimum)
Collector-emitter breakdown voltage (40V minimum)
DC current gain (hFE ≥ 100 @ 10mA, 1V)
Operating temperature range (-55°C to 150°C minimum)

Mechanical Parameters:

Surface mount packaging (SC-88, SOT-363, or 6-TSSOP equivalent)
Pin configuration compatibility with SC-70-6 footprint

Substitute parts are grouped into two categories:

Direct Equivalents (onsemi MBT3946 series): Parts MBT3946DW1T1G, MBT3946DW1T2G, and SMBT3946DW1T1G maintain identical electrical specifications and package compatibility. These parts differ only in packaging format (Cut Tape vs. Tape & Reel) and are active products with RoHS3 compliance.

Functional Equivalents (Cross-manufacturer alternatives): Parts MMDT3946-7-F, MMDT3946-7R-F, CMKT3946 TR PBFREE, BC847PN-7-F, MMDT3904-TP, and MMDT4413-7-F meet the core electrical requirements within the specified parameter ranges while originating from different manufacturers. These parts maintain the 40V breakdown voltage, 200mA collector current capability, and complementary transistor configuration.

Parameter Comparison

Part Number	Manufacturer	Ic (Max) mA	Vce(br) V	hFE Min @ Ic, Vce	Power Max mW	Freq MHz	Temp Range °C	Package	Status
FFB3946	onsemi	200	40	100 @ 10mA, 1V	300	200	-55 to 150	SC-88, SOT-363	Obsolete
MBT3946DW1T1G	onsemi	200	40	100 @ 10mA, 1V	150	300, 250	-55 to 150	SC-88, SOT-363	Active
MBT3946DW1T2G	onsemi	200	40	100 @ 10mA, 1V	150	300, 250	-55 to 150	SC-88, SOT-363	Active
SMBT3946DW1T1G	onsemi	200	40	100 @ 10mA, 1V	150	300, 250	-55 to 150	SC-88, SOT-363	Active
MMDT3946-7-F	Diodes Incorporated	200	40	100 @ 10mA, 1V	200	300, 250	-55 to 150	SOT-363	Active
MMDT3946-7R-F	Diodes Incorporated	200	40	100 @ 10mA, 1V	200	300, 250	-55 to 150	SOT-363	Active
CMKT3946 TR PBFREE	Central Semiconductor Corp	200	40	100 @ 10mA, 1V	350	300, 250	-65 to 150	SOT-363	Active
BC847PN-7-F	Diodes Incorporated	100	45	200 @ 2mA, 5V	200	300, 200	-65 to 150	SOT-363	Active
MMDT3904-TP	Micro Commercial Co	200	40	100 @ 10mA, 1V	200	300	-55 to 150	SOT-363	Active
MMDT4413-7-F	Diodes Incorporated	600	40	100 @ 150mA, 1V	200	250, 200	-65 to 150	SOT-363	Active

Engineering Selection Recommendations

Primary Recommendation: onsemi MBT3946 Series

The MBT3946DW1T1G, MBT3946DW1T2G, and SMBT3946DW1T1G represent the most direct substitutes for the obsolete FFB3946. All three parts are manufactured by onsemi, the original FFB3946 manufacturer, and maintain identical electrical specifications including 200mA collector current, 40V breakdown voltage, and 100 hFE minimum. These parts are active products with RoHS3 compliance and REACH unaffected status. Selection between these three variants depends on packaging format requirements: MBT3946DW1T1G and SMBT3946DW1T1G are supplied in Cut Tape format, while MBT3946DW1T2G is supplied in Tape & Reel format. All three operate across the -55°C to 150°C temperature range and are MSL 1 rated.

Secondary Recommendation: Diodes Incorporated MMDT3946 Series

The MMDT3946-7-F and MMDT3946-7R-F from Diodes Incorporated provide functional equivalence with identical electrical parameters to the onsemi MBT3946 series. Both parts maintain 200mA collector current, 40V breakdown voltage, and 100 hFE minimum specifications. The MMDT3946-7-F is supplied in Cut Tape format, while MMDT3946-7R-F is supplied in Tape & Reel format. These parts are active, RoHS3 compliant, and operate across the -55°C to 150°C temperature range.

Alternative Recommendation: Central Semiconductor CMKT3946

The CMKT3946 TR PBFREE from Central Semiconductor Corp meets all core electrical requirements with 200mA collector current and 40V breakdown voltage. This part offers extended power dissipation capability (350mW vs. 300mW) and an expanded operating temperature range (-65°C to 150°C). The part is active and RoHS3 compliant.

Limited Substitution: BC847PN-7-F

The BC847PN-7-F from Diodes Incorporated operates at reduced collector current (100mA maximum vs. 200mA) and exhibits higher DC current gain (200 hFE minimum vs. 100). This part is suitable only for applications where the lower current rating is acceptable. The part is active and RoHS3 compliant with an extended temperature range (-65°C to 150°C).

Limited Substitution: MMDT3904-TP

The MMDT3904-TP from Micro Commercial Co is a dual NPN configuration without the complementary PNP transistor present in the FFB3946. This part is suitable only for applications requiring dual NPN functionality. The part maintains 200mA collector current, 40V breakdown voltage, and 100 hFE minimum specifications. It is active and RoHS3 compliant.

Limited Substitution: MMDT4413-7-F

The MMDT4413-7-F from Diodes Incorporated operates at elevated collector current (600mA maximum vs. 200mA) and is suitable only for applications requiring higher current capability. The part maintains 40V breakdown voltage and 100 hFE minimum specifications. It is active and RoHS3 compliant with an extended temperature range (-65°C to 150°C).

Frequently Asked Questions (FAQ)

Q: Can MBT3946DW1T1G directly replace FFB3946 in existing designs?

A: Yes. The MBT3946DW1T1G maintains identical electrical specifications (200mA Ic, 40V Vce(br), 100 hFE minimum) and package compatibility (SC-88, SOT-363). The primary difference is packaging format (Cut Tape vs. the original format). Both parts are MSL 1 rated and operate across -55°C to 150°C.

Q: What is the difference between MBT3946DW1T1G and MBT3946DW1T2G?

A: Both parts are electrically identical. The difference is packaging format: MBT3946DW1T1G is supplied in Cut Tape & Digi-Reel format, while MBT3946DW1T2G is supplied in Tape & Reel format. Selection depends on manufacturing process requirements.

Q: Can MMDT3946-7-F be used instead of MBT3946DW1T1G?

A: Yes. Both parts maintain identical electrical specifications (200mA Ic, 40V Vce(br), 100 hFE minimum) and package compatibility (SOT-363). The MMDT3946-7-F is manufactured by Diodes Incorporated rather than onsemi. Both are active products with RoHS3 compliance.

Q: Why is BC847PN-7-F listed as a limited substitute?

A: The BC847PN-7-F operates at reduced maximum collector current (100mA vs. 200mA) and exhibits higher DC current gain (200 hFE minimum vs. 100). This part is suitable only for applications where the lower current rating does not exceed design requirements.

Q: Is MMDT3904-TP a suitable replacement for FFB3946?

A: The MMDT3904-TP is a limited substitute. It is a dual NPN configuration without the complementary PNP transistor present in the FFB3946. It is suitable only for applications requiring dual NPN functionality. Electrical specifications for the NPN portion (200mA Ic, 40V Vce(br), 100 hFE minimum) are maintained.

Q: What does MSL 1 rating mean for these transistor arrays?

A: MSL (Moisture Sensitivity Level) 1 indicates unlimited shelf life with no moisture bake requirement prior to soldering. All listed substitute parts carry MSL 1 rating, matching the FFB3946 specification.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All active substitute parts listed (MBT3946DW1T1G, MBT3946DW1T2G, SMBT3946DW1T1G, MMDT3946-7-F, MMDT3946-7R-F, CMKT3946 TR PBFREE, BC847PN-7-F, MMDT3904-TP, and MMDT4413-7-F) are RoHS3 compliant and REACH unaffected.

Q: Can MMDT4413-7-F be used in place of FFB3946?

A: The MMDT4413-7-F is a limited substitute. It operates at elevated collector current (600mA maximum vs. 200mA) and is suitable only for applications requiring higher current capability. The 40V breakdown voltage and 100 hFE minimum specifications are maintained.

Q: What is the operating temperature range for substitute parts?

A: Most substitute parts operate across -55°C to 150°C, matching the FFB3946. Extended range options include CMKT3946 TR PBFREE, BC847PN-7-F, and MMDT4413-7-F, which operate across -65°C to 150°C.

Q: Are there inventory differences between substitute parts?

A: Yes. Inventory levels vary by part number and supplier. MBT3946DW1T1G has 98,400 units in stock, MMDT3946-7R-F has 68,400 units, and SMBT3946DW1T1G has 47,300 units. Availability should be confirmed with the component supplier for production requirements.

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